This invention relates to a process for the production of dinitrophenyl ethers, and more particularly to the process for the production of dinitrophenyl ethers represented by the following general formula [III]: ##STR3## wherein, one of R.sub.1 and R.sub.2 is a nitro radical, and the other is a hydrogen atom or a straight-chain, branched-chain or cyclic saturated or unsaturated hydrocarbon radical containing from 1 to 10 carbon atoms, and R.sub.3 is a radical selected from the group consisting of (i) a straight-chain, branched-chain or cyclic, saturated or unsaturated hydrocarbon radical containing from 2 to 10 carbon atoms, (ii) a straight-chain hydrocarbon radical having one phenyl group as a substituent and containing from 1 to 5 carbon atoms, (iii) a phenyl radical, and (iv) a phenyl radical with one or more than one substituents selected from the group consisting of a nitro group, a halogen group, a saturated or unsaturated hydrocarbon group containing from 1 to 5 carbon atoms and an alkoxy group containing from 1 to 4 carbon atoms.
Dinitrophenyl ethers obtained by the process according to the invention include known compounds and novel compounds. As to such dinitrophenyl ethers, for example, 2,4-dinitrophenyl ether is described in British Patent Specification No. 1279874 (1969), and 2,6-dinitrophenyl ether is described in Japanese Open-laid Patent Specification No. SHO 56-2901 (1981). These prior literature references are, however, related to the activities of the corresponding dinitrophenyl ether compounds as agricultural chemicals, and the synthetic processes for preparation of these compounds are not studied. The synthetic process described in the said British Patent is, therefore, only to carry out the general classic known processes (described later). The said general known processes are the following two:
(1) a process for reacting dinitrophenols and a halogenated hydrocarbon in the presence of an equal molar or more than equal molar alkali, and (2) a process for reacting dinitrohalobenzene and an alcohol in the presence of strong alkaline liquid. In both processes, therefore, it is necessary to prepare the halogenated compounds beforehand and to use a large quantity of the alkaline substances. Furthermore, the above-mentioned two processes have a disadvantage such that the synthesis of the compounds having as R.sub.3 a phenyl radical with a substituent as in the above-mentioned formula [III] is not possible.
Because of the above-mentioned conditions, if any compound having a high activity as agricultural chemicals is found among dinitrophenyl ethers in the future, it is difficult to produce that compound advantageously from the viewpoint of economics. The inventors have studied to solve the above-mentioned technical problems concerning the process for production of dinitrophenyl ethers. Consequently, they have found that the objective compounds can be obtained more easily as to their procedures and also in better yield than the classic processes, by using dinitrophenyl methyl ether and the specified alcohol as raw materials as well as a catalytic amount of an alkaline compound.
As seen clearly from the aforesaid description, the invention provides novel synthetic process of preparing dinitrophenyl ethers without using any halogen compound as an intermediate. Another object is to provide the said synthetic process by which the objective compounds can be obtained in higher yield than the conventional processes which use a halogen compound as an intermediate. The other objects will become clear from the following description.